Sadly, there is no way that I know of to do that other than trying natural options for hair lightning such as lemon, honey and chamomile. There are many recipies out there to do this not everything works for everyone you will just have to goolge and try them out. Once you get the color or lighter shade you want if you want to stay on the light side dye release cassia and make that predominant in your mix because continued straight henna applications will darken your hair right back, you will have dark red hair but it will still be dark. Cassia will add golden tones and not darken. Good luck.

If henna is on cloth, it may not come out, you may have to try bleaching it out. A lot of folks use henna to stain cloth. Once it is on the hands, it can stay there for a few days or a few weeks depending on how long it was on the hand for.